Extrusion of filament-forming materials



Nov. 3, 1953 E. J. UPTON 2,657,427

EXTRUVSION OF FILAMEINT-FORMING MATERIALS Filed July 11, 1951 Z'Sheets-Sheet 2 Inventor Attorneys i atented Nov. 3, 195

UNITED STATES PATENT OFFICE EXTRUSION OF FIIl'AMENT-FORMING MATERIALS Edward James Upton, Spondon, near Derby, England, assignor to British Celanese Limited, a corporation of Great Britain Application July 11, 1951, Serial No. 236,130 3 Claims priority, application 'Great Britain f 1 July 19,1950

8 Claims.

This invention relates to the extrusion of filament-forming materials and particularly to a method and apparatus for extruding'powdered or granular fusible filament-forming material, and is an improvement in or a modification of the method and apparatus described in US. application S. No. 115,035, filed September 10, 1949.

According to the present invention a method of extruding powdered or granular fusible filament-forming' material comprises-feeding the material into a zone laterally bounded at least .part-way round by moving surfaces which lie .substantially parallel to their directionof motion,

and compacting the material in an early part of said zone so as to. form it into a coherent rod and to force it into frictional engagement with said surfaces whereby said rod is advanced with said surfaces, said surfaces being rigidly supported in said early part of said zone, and being resiliently urged inwards of said zone in a later part of said zone, whereby said frictional engagement is maintained in said'later part. As in the parent U. S. application S. No. 115,035, the advancing rod can be received, as it leaves the surfaces, into a laterally confined space leading to one or more extrusion orifices, the end of the rod being meltedin said confined space whereby the. molten. material is extruded through said orifices by the prescure of the advancing, rod.

An apparatus for carrying outithe method defined above comprises .two endless flexible membersarranged to travel past a zone .over which they present to each other opposed continuous .surfaces each substantially parallel to acommon centre, line, means for rigidly supporting said members behind saidparallel surfaces over a part of said zone, means for resiliently supporting at least one of said members behind said-parallel surfaces over a later part of said zone, means for feeding the material into the space between said members and for compacting it into a rod in the first-mentioned partof said zone, and means for driving said members so as to forward the compacted rod.

By the method and mans'described above the material is compacted into a rod in the first part of a parallel-sided passage, constituting the zone referred to above, whose boundaries are the moving surfaces of the flexible members; the frictional engagement brought about ab initio between the compacted rod and the moving surfaces is maintained over the whole length of the passage, notwithstanding the possibility of slight irregularities in the widthof the passage, or of a slight yielding of the substance of the compacted rod. This ensures the distribution of the applied force, necessary for forwarding the rod through a heated extrusion head, over the whole length of the rod contained in the passage. If, as is generally convenient, the passage is partly bounded by stationary walls, these may be arranged to diverge slightly from the centre line of the pas- ,sage instead of being exactly parallel thereto, or

to be relieved slightly following the early part of the passage, so that the frictional engagement of the rod with the stationary surfaces is eased rather than maintained as the rod moves along the passage, and the forwarding of the rod is facilitated. This makes it unnecessary to provide elaborate means for making as many as possible of the bounding surfaces of the passage moving boundaries. Nevertheless, though only two surfaces, opposed to one another, need to be moving surfaces, it is preferred that the passage should be of a rectangular cross-section of which the moving surfaces constitute the longer sides,

so as to minimise the area of the stationary surfaces.

The compacting of the granular material inthe zone constituted by the passage is conveniently carried out by means of a tamping rod or like member, vibrating longitudinally with its tip dis- I posed between the endless flexible members and surfaces are rigidly supported. Feeding of the material to a tamp'ing rod of this kind can be eftamping the material by repeated impacts in the early part of the zone, over which theparallel fected, from one or both sides of the passage,

7 through the stationary walls of the passage by way of an oblique downwardly extending hopper or feed passage communicating through the stationary wall to a point below the uppermost position of the tip of thetamping rod. In order to ensure a steady feed of the material the arrangements described in co-pending U. ,8. application s. No. 236,129, filed July 11, 1951, may be employed, in which, when the level of the material supplied is low, a consequent change in the mode of motion of the vibrating rcdis utilised to effect aeema'i Figure 2 is a front elevation of the apparatus, partly in section, showing an extrusion head associated with the apparatus and also the vibrator mechanism omitted from Figure 1.

The apparatus comprises a pair of endless triple roller chains 5, 6 each driven by a pair of sprockets l, 8 each pair of sprockets being mounted on a common shaft 9, Ill. The apparatus as shown in Figure 1 is one of a series of units ranged in line and disposed in pairs as may be seen from Figure 2, each pair being provided with a common drive. The common drive is contained in a gear box H, the shaft 9, It being mounted in bearings [2 in opposite walls of the gear box and bein common to the two units. The essential parts of the mechanism of the present invention are contained in a casing 13, one of which is fixed on each side of the gear box ll, each of the casings being provided with a cover plate l4 by which the mechanism is enclosed. The shaft 9 is driven from a shaft l5 entering the gear box H from the rear, and carrying a worm i6 engaging a worm gear ll mounted on a shaft :8 in the gear box. The worm gear H is secured to a pinion l9 engaging a gear freely mounted on the shaft e and secured to a pinion 2|. The pinion engages a gear 22 freely mounted on the shaft l8 and secured to a further pinion 23 engaging a gear 24 which is keyed to the shaft 9. also engages a gear of equal size (not shown) keyed to the shaft Ii] so that the shafts 9, ii! are driven in synchronism with one another.

The chains 5, 6 are each trained round three idler pulleys 36}, Si and 32 the pulley 3% being a spring-loaded jockey pulley, mounted in a bearing block 33 urged upwards by a spring 34 which is adjustable by means of a screw 35. Each chain 5, 6 carries a series of blocks 33 secured to the middle rollers of the chain. The

back of each block 38 is channelled to clear the flat links of the chain 5, 6, but engages and is supported by the rollers of all three lines of rollers in the chain. The operative runs of the two chains 5, 6 are substantially vertical, close to the centre line of Figure 1 and one on each side thereof, the chain moving downwards over this run. The faces of the blocks 36 are covered by two flexible stainless steel bands so, ll! which leave the blocks between the pulleys 3G, 3! to pass round independent jocket pulleys ti carried in bearing blocks 42, spring loaded by means of adjustable springs 43.

The chain 5 is supported over its operative run by means of a fixed supporting block 44 accurately located and secured to the wall of the gear box ll. At the bottom of the block 34 is a separate piece 45, cut away to accommodate the pulley 32, the block 44 extending down each side of the piece 45 and the pulley 32, the spindle of which passes through the extensions. The block 44 and piece 45 are both channelled and support the chain 5 by the engagement of their edges. The block 44 and piece 415 solidly support the chain 5 over the whole of its operative run from the pulley 3! to the pulley 32.

The operative run of the chain 5 is supported by a series of blocks 48, 49, 5i}, 5! which are slidably mounted in apertures in a fixed block 52 accurately located and secured to the wall of the gear box Ii. The attachment of the block 43 is effected by means of screws 54, passing through a backing plate 55 which engages behind the uppermost aperture in the block 52, and entering the back of the block 43. The block 48 is thus The gear 24 4 solidly mounted, and supports the chain 6 rigidly in the same way as the block 44 supports the chain 5. The blocks 59, to and. El, however, are not mounted rigidly but resiliently, being slidable in their apertures in the block 52 and being backed separately by plates 56 each of which is urged into engagement with its block 4-9, 59 01' 5| by a pair of strong springs 57. The springs 51 are mounted on studs 58 located in holes 59 in a block so accurately located and secured to the wall of the gear box H. The block 69 carries the bearing block 33 for the jockey pulley 3i} engaging the chain 6, and is cut away at the bottom right-hand corner to accommodate the shaft Ill. The lowermost aperture in the locating block 52, accommodating the lowermost block 5|, extends to the bottom of the block 52, so as to accommodate also the idler pulley 32, the shaft of the pulley passing through the extension of the block 52 on each side thereof. In order to locate the block 5| vertically, horizontal ridges 6d are formed in each of its sides, fitting into horizontal channels in the extensions of the lower end of the block 52. Each of the blocks it-5i is channelled, like the block ts, for the support of the outer line of rollers of the chain 6.

The space 63 between the operative runs of the chains 5 and 6, which space is bounded on two sides by the surfaces of the bands 39, 4B, is bounded on the other two sides by guide plates 64, as and upper cheek plates st, 5'6 (Figure 2) and lower cheek plates 63, 69 (Figure 2). The lower cheek plates 68, 6!; are bolted directly to the wall of the gear box ll, and the cover plate M respectively and the guide plates 64, 65 are similarly secured. The upper cheek plates 86, 61 are also bolted to the members i i, M respectively but are spaced at a little distance from the members by means of shims i8 so as to be a little closer together than the cheek plates 58, 69, by an amount that can be adjusted by changing the shims '50.

For the feeding of powdered or granular material into the space 63, passages H, 72 are formed through the lower ends of the guide plates 64, 65, the lower sides of the passages being constituted by the upper surfaces of the cheek plates 66, G7. The passages H, F2 are led into by ducts i3 supplied from hoppers M, one hopper being common to each two adjacent units. The passage H extends through the guide plate 54, and also through the wall of the gear box I i and through an inner cover plate 15 disposed inside the gear box II, to which cover plate a duct 13 is secured. Similarly the passage 12 extends through the guide plate 65, through the cover plate 14, and through an outer cover plate F6 to which another duct '53 is secured. Between the cover plate l5 and the wall of the gear box H is disposed a feed gate H extending part-way across the passage 'i'l, while between the cover plate [4 and the cover plate 76 is disposed a similar gate extending part-way across the passage 12. The cover plates l5, 16 are channelled on their inner faces to acommodate the gates 11.

In the passage 53 is disposed a vibrating tamping rod 80 actuated by a pneumatic vibrator 8!, e. g. of the kind used for the agitation of mould boxes in foundry work, supplied with compressed air by a pipe 82. The tamping rod 80 is guided by the plates 64, 65, and at the bottom of its throw its tip enters between the upper cheek plates 56, E1. The gates 71 are carried on a yoke 84 having lugs 85 (Figure l) which are guided by slots 86 in the standards 81 carrying the vibrator 8L 'The yoke 84 is urged downwardsto the bottom of the slots 86 by means of a light spring 88 engaging beneath the vibrators I. A flanged tube 89 is screwed intothe bore 96 of the yoke 82 through which the vibrator rod 80 extends, and

is locked in adjustable position by means of a lock nut 2i. Shoulders 92 are provided on the tamping rod 8% which are adapted, on occasions, to engage the lower edge of the tube 89. These occasions arise in the event of ajamming 'or bridging of the powdered or granular material in the ducts '53, in which case the passage 63 is starved of material and the tamping rodiill, having greater freedom of play downwards, reacts more freely upwards so that the tube 89 is engaged by the shoulders 92. When this takes place, the gates TI which limit the flow of granularmaterial through the ducts I3 are lifted so as to release the jam. When the supply of powdered or granular material is suificient, the field of motion of the tamping rod 82 is limited andthe shoulders casing I3 and leading to an extrusion head indicated generally at 95' (in the left-hand side of Figure 2. The extrusion head 86 is shown in greater detail on the right-hand side of Figure 2, inwhich the two sides of the'head are shownsectioned in two planes at right angles to one another. The head comprises an inlet tube 91 secured to the guide passage 95 by means of a flange 88 engaging beneath a split ring 99 fitting into a groove round the mouth of the inlet tube 9?. The flange is drawn upwards by means of nuts I on the screws IBI through which the guide passage 95 is secured to the casing I3. The inlet tube 9i extends into a vapour jacket I04, entering through a heat-resisting pressure gland I05, and communicates with a melt tube I06 of thin section, the lower part of which converges (as shown on the right-hand side of the head) and leads into a filter unit contained in a casing I08. The jacket Iil is heavily lagged as at I99 and contains a liquid H6 (such as diphenyl or diphenyl oxide or an azeotropic mixture thereof) which is vaporized in the upper part of the jacket I04 by heat supplied through electrical windings III. The supply or" energy to the windings I II is controlled so as to maintain a constant pressure of the vapour in the jacket I04, as measured through a pressure take-oil passage H2. In this way a constant and controlled temperature is maintained in the jacket I04.

The filter and jet casing I28 contains a stainless steel shell Ii i at the top of which two 60 mesh stainless steel gauzes I I5 are held beneath a screwed ring H6. Beneath the gauzes H5 is a sand bed I I? of washed sand of a size which will pass a 16 mesh gauze but not a 32 mesh gauze. A clamp ring H8 inside the shell H4 screws down on a series of gauzes H9 comprising two 200 mesh stainless steel gauzes, six 300 mesh Phosphor bronze gauzes and one 200 mesh stainless steel gauze. The bottom of the shell I54 terminates in a slightly tapered boss I29 through which pass a central hole I2I, and twelve circumferential holes 522 breaking out into the tapered sides of 'the boss. Over the boss ltd is fitted a dished jet I23 secured in place by means of a nut I22.

The jet a'nd'filter assembly is secured as a unit ""in' the casing I03 by means of a nut I25. By removing the filter and jet assembly, and the split ring 99, the entire inlet tube 91 and melt tube I25 can be readily removed for cleaning.

In the operation of the apparatus powdered or'granularmat'eri'al is fed to the hoppers I4 and passes -through the ducts "I3 and the passages I ll, 12 into "the passage 63 between the bands 39,

ll and between the upper cheek plates 66, 67.

The powder is tamped by the tip of the tamping rod 8Il'into a compacted rod of rectangular section in the part of the passage 63 over which the band i!) is rigidly supported by the block 18 and,

by the tamping action, is brought into firm frictional engagement with the bands so that the compacted 'rod'is carried by'the bands down'the passage 63. Below the block as the frictionalengagement of the bands 39, 49 with the compacted rod is maintained by the resilienceof the springs 51 which urge the blocks 38; 50, 5| inwards. At the same time the frictional engagement'of the other two sides of the rod with the upper cheek plates I56, Ii! is relieved as the compacted rod reaches the lower cheek plates 68, 69.

The friction between the compacted rod and the bands 39, 40 is therefore considerable and the movement of the bands is sufficient to force the compacted rod through the guide passage and the inlet tube 97,- into the diminishing cross-sec- ":tiori of the melttube I06. In the melt tube the "material of the compacted rod is fused and -the are set by cooling and collected in any convenient way.

As in the parent U. S. application S. No. 115,035, the invention is particularly adapted for the extrusion of organic filament-forming materials that are liable to decompose at temperatures at or only slightly above their melting points, e. g. synthetic linear polyamides, made for example by the condensing of diamines with dicarboxylic acids, or the synthetic polyaminotriazoles (such as polyocta-methylene-aminotriazole) made for example as described in U. S. Patents Nos. 2,512,600 and 2,512,667 or co-polyamide-aminotriazoles, made for example as described in U. S. Patent No. 2,512,627. The invention may also be applied, however, to the spinning of other fusible filament-forming materials, e. g. polyvinyl compounds such as polyvinylidene chloride and copolymers of vinyl chloride with vinyl acetate or aorylonitrile.

Having described my invention, what I desire to secure by Letters Patent is:

1. A method of extruding powdered or granular fusible filament-formin material, said method comprising feeding the material into a zone laterally bounded at least part-way round by moving surfaces which lie substantially parallel to their direction of motion, compacting the material in an early part of said zone so as to form it into a coherent rod and to force it into frictional engagement with said surfaces whereby said rod is advanced with said surfaces, leading the advancing rod as it leaves said surfaces into a laterally confined space having a maximum cross-section substantially equal to that of said 7, rod and leading to at least one extrusion orifice, melting the end of said rod in said confined space whereby the molten material is extruded through said orifice by the pressure of the advancing rod, rigidly supporting the material inwards of said moving surfaces in said-early part of said zone and resiliently urging the compacted rod inwards of said moving surfaces in a later part of said zone whereby said frictional engagement is maintained in said later part and the applied force necessary to produce said pressure is distributed over the Whole length of said zone.

2. Method according to claim '1 comprising tamping the material by repeated impacts directed longitudinally of said zone in the early part of the zone so as to compact the material.

3. Apparatus for the extrusion of powdered or granular fusible filament-forming material, said apparatus comprising two endless flexible members arranged to travel past a zone over which they present to each other opposed continuous surfaces each substantially parallel to a common centre line, means for rigidly supporting said members behind said continuous surfaces over a part of said Zone, means for resiliently supporting at least one of said members behind said continuous surfaces over a later part of said zone, means for feeding the material into the space between said members and for compacting it into a rod in the part of said zone where said members are rigidly supported, means for driving said members so as to forward the compacted rod, and a heated extrusion head adapted to receive the compacted rod and to melt said rod, said extrusion head being formed with at least one extrusion orifice, through which the molten material is forced by the pressure of the advancing rod.

4. Apparatus according to claim 3 comprising a tamping rod with its tip disposed between the endless flexible members, and means for vibrating said rod longitudinally so as to tamp the granular material into a rod.

5. Apparatus according to claim 3 comprising stationary Walls co-operating with the endless flexible members to constitute a passage 6. Apparatus according to claim 3 comprising stationary walls co-operating with the endless flexible members to constitute a passage and formed With at least one feed passage therein for the supply of fresh material to the said passage.

7. Apparatus according to claim 6 comprising a tamping rod with its tip disposed between the endless flexible members, means for vibrating said rod longitudinally so as to tamp the granular material into a rod and means adapted to be engaged by said tamping rod upon excess upward motion thereof and to communicate said excess motion to the feed passage so as to encourage the flow of fresh material.

8. Apparatus according to claim 7 comprising a gate extending across the feed passage and adapted to be moved upon excessive motion of the tamping rod.

EDWARD JAMES UPTON.

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